The primary objective of the present invention is to provide a suitable non-metallic electrical carbon fiber tow heating element assembly to enable participation in a large portion of the heating element market, namely that portion of the market producing products requiring heat output in the range of 200 to 600 degrees F. Heretofore terminations have been developed for various forms of carbon fiber, however such carbon fiber heating element assemblies usually employ some form of mechanical clamping utilizing a metal plate or plates clamped together in holding engagement by threaded fasteners or adjustable fasteners of other types. Such terminations are generally difficult and expensive to make and are often prone to premature failure.
Two earlier patents to Applicant and relating to non-metallic electrical terminations, U.S. Pat. No. 6,135,829 for Electrical Connection and U.S. Pat. No. 5,857,259 for Method for Making an Electrical Connection, are concerned with technology originally developed for the production of high density electrical termination assemblies and heating applications for the low temperature end of the heating spectrum (100-170 degrees F.) and work well at current limits of 1.5 amperes or less. However the need for new technology becomes apparent after extensive testing of companion carbon fiber electrically terminated product assemblies fail to adequately perform when applying higher amperage (2 to 5 amps) to the tow form of carbon fiber. Unlike other forms of carbon fiber, mainly, inks, mats, broken strand yarn bundles and woven surfaces, all of which feature consistent and uniform surface fiber configuration, the carbon fiber tow form proves virtually impossible to confine in an exacting level position prior to the application of ultrasonic energy required to weld such a plastic termination system together. Due to the relatively high resistance of the carbon fiber tow it is concluded that a single wire mating surface area is insufficient to enable a suitable high current electrical termination.